I have an ASMB4-iKVM. I think it's this, although it has two stickers
and I can not see the concrete model

If you got your D16 new it comes with one (so that is probably what you
have) - its a tiny little module that attaches next to the PCI-e slots -
see the manual for a photo.
This is one of the reasons I always advise people to buy a new D16 as
that module is very hard to find despite being so simple.

I imagine it could be easily reverse engineered and copied for those who
don't have one, although I lack the time and have never done that sort
of thing before.

re: 6328 - please be aware that this has two NUMA nodes (it is two 4
core CPU's in a single package) and that games won't work well if you
don't properly align the memory to have the games memory present on only
one node (this appears to be the best arrangement)
For gaming I imagine that a C32 board like the KCMA-D8 and one or two of
the single node/MCM opteron 4386 would be better but I run games on a
dual numa setup in a VM without much issues - I am able to max out
newish video games with a decent graphics card (the board also supports
crossfire if you have mad money to burn on GPU's)